Na+ and Ca2+ Effect on the Hydration and Orientation of the Phosphate Group of DPPC at Air−Water and Air−Hydrated Silica Interfaces

Casillas-Ituarte, Nadia N.; Chen, Xiangke; Castada, Hardy Z.; Allen, Heather C.

doi:10.1021/jp1022357

Cited by 93 publications

(139 citation statements)

References 98 publications

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“…When it is fully dehydrated (CWT = 0), Na + can be bound to at most 7 lipid oxygens. Between these two extreme cases, Na + is bound to oxygens [2,6] with the total coordination number (CLP+CWT)∈ [5,7].…”

Section: Resultsmentioning

confidence: 99%

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Specific Ion Binding at Phospholipid Membrane Surfaces

Yang

Calero

Bonomi

et al. 2015

J. Chem. Theory Comput.

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Metal cations are ubiquitous components in biological environments and play an important role in regulating cellular functioning and membrane properties. By applying metadynamics simulations, we have performed systematic free-energy calculations of Na + , K + , Ca 2+ , and Mg 2+ bound to phospholipid membrane surfaces for the first time. The free-energy landscapes unveil specific binding behaviors of metal cations on phospholipid membranes. Na + and K + are more likely to stay in the aqueous solution, and can easily bind to a few lipid oxygens by overcoming low free-energy barriers. Ca 2+ is most stable when bound to four lipid oxygens of the membranes, rather than being * To whom correspondence should be addressed † Technical University of Catalonia-Barcelona Tech ‡ Boston University ¶ University of Cambridge 1 hydrated in the aqueous solution. Mg 2+ is tightly hydrated, and can hardly lose a hydration water and bind directly to the membranes. When bound to the membranes, the cations' most favorable total coordination numbers with water and lipid oxygens are the same as their corresponding hydration numbers in aqueous solution, indicating a competition between ion binding to water and lipids. The binding specificity of metal cations on membranes is then highly correlated with the hydration free-energy and the size of the hydration shell.

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Section: Resultsmentioning

confidence: 99%

“…[5][6][7][8] While bound to membranes in aqueous solution, a hydrated metal cation will lose one or more water molecules from its first hydration shell, resulting in several possible bound configurations. 9,10 Although the binding constant and…”

mentioning

confidence: 99%

Specific Ion Binding at Phospholipid Membrane Surfaces

Yang

Calero

Bonomi

et al. 2015

J. Chem. Theory Comput.

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“…Therefore, a bound state can be characterized by the ion's coordination number with lipid binding sites and its simultaneous coordination number with water molecules. A number of experiments [3][4][5][6] and simulation works [6][7][8][9][10][11][12][13] have indicated that metal cations bind directly to the oxygen atoms of the negative charged phosphate (PO − 4 ) and carbonyl (C=O) groups of lipid molecules. Accordingly, we defined two collective variables (CVs) to describe the ion's bound states: the coordination number between a Na + ion and lipid (including cholesterol) oxygens (CLP), and the coordination number between a Na + ion and water oxygens (CWT).…”

Section: Collective Variablesmentioning

confidence: 99%

“…Several experiments revealed that metal cations are bound to the negative charged head groups of phospholipid membranes [3][4][5][6] . Meanwhile, numerous molecular dynamics (MD) simulations have been performed to study the binding of metal cations at phospholipid membranes from an atomic point of view [6][7][8][9][10][11][12][13] .…”

Section: Introductionmentioning

confidence: 99%

Free energy landscapes of sodium ions bound to DMPC–cholesterol membrane surfaces at infinite dilution

Yang

Bonomi

Calero

et al. 2016

Phys. Chem. Chem. Phys.

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Exploring the free energy landscapes of metal cations on phospholipid membrane surfaces is important for the understanding of chemical and biological processes in cellular environments. Using metadynamics simulations we have performed systematic free energy calculations of sodium cations bound to DMPC phospholipid membranes with cholesterol concentration varying between 0% (cholesterol-free) and 50% (cholesterol-rich) at infinite dilution. The resulting free energy landscapes reveal the competition between binding of sodium to water and to lipid head groups. Moreover, the binding competitiveness of lipid head groups is diminished by cholesterol contents. As cholesterol concentration increases, the ionic affinity to membranes decreases. When cholesterol concentration is greater than 30%, the ionic binding is significantly reduced, which coincides with the phase transition point of DMPC-cholesterol membranes from a liquid-disordered phase to a liquid-ordered phase. We have also evaluated the contributions of different lipid head groups to the binding free energy separately. The DMPC's carbonyl group is the most favorable binding site for sodium, followed by DMPC's phosphate group and then the hydroxyl group of cholesterol.

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“…Several studies have shown that the replacement of a pure water subphase with inorganic salt solutions causes alterations in the phase behavior of the monolayer, especially for FAs and phospholipids [31][32][33][34][35][36][37]. The effect of Ca 2+ has been widely investigated due to its relevance in biological membranes [38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Palmitic Acid on Salt Subphases and in Mixed Monolayers of Cerebrosides: Application to Atmospheric Aerosol Chemistry

Adams

Allen

2013

Atmosphere

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Palmitic acid (PA) has been found to be a major constituent in marine aerosols, and is commonly used to investigate organic containing atmospheric aerosols, and is therefore used here as a proxy system. Surface pressure-area isotherms (π-A), Brewster angle microscopy (BAM), and vibrational sum frequency generation (VSFG) were used to observe a PA monolayer during film compression on subphases of ultrapure water, CaCl 2 and MgCl 2 aqueous solutions, and artificial seawater (ASW). π-A isotherms indicate that salt subphases alter the phase behavior of PA, and BAM further reveals that a condensation of the monolayer occurs when compared to pure water. VSFG spectra and BAM images show that Mg . π-A isotherms and BAM were also used to monitor mixed monolayers of PA and cerebroside, a simple glycolipid. Results reveal that PA also has a condensing effect on the cerebroside monolayer. Thermodynamic analysis indicates that attractive interactions between the two components exist; this may be due to hydrogen bonding of the galactose and carbonyl headgroups. BAM images of the collapse structures show that mixed monolayers of PA and cerebroside are miscible at all surface pressures. These results suggest that the surface morphology of organic-coated aerosols is influenced by the chemical composition of the aqueous core and the organic film itself.

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Na⁺ and Ca²⁺ Effect on the Hydration and Orientation of the Phosphate Group of DPPC at Air−Water and Air−Hydrated Silica Interfaces

Cited by 93 publications

References 98 publications

Specific Ion Binding at Phospholipid Membrane Surfaces

Specific Ion Binding at Phospholipid Membrane Surfaces

Free energy landscapes of sodium ions bound to DMPC–cholesterol membrane surfaces at infinite dilution

Palmitic Acid on Salt Subphases and in Mixed Monolayers of Cerebrosides: Application to Atmospheric Aerosol Chemistry

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